It was disappointing this past week to learn that Britain's Prime Minister David Cameron is planning to go ahead with a scheme to censor his citizens' access to the internet. His statements were accompanied by the same tired refrain that we have heard many times in the past: "[I'm doing it] for the children."

If the prime minister's assertion sounds familiar to us in South Africa, it is because it is this same logic that was used to ban the film Of Good Report (now unbanned, on appeal).
Our Film and Publications Board felt that censoring a work of genuine artistic merit was an acceptable cost for cracking down on child pornography. Cameron's plan has similar roots. He claims that censoring the internet is necessary to stop illegal pornography from being accessed by paedophiles, and the film and publication board's actions leave me concerned that local legislators might attempt to follow Cameron's lead.

My first point is the most important, so I'm going to state it unambiguously right at the start: censoring the internet will not have even the slightest effect on child pornography, its creation, distribution or popularity. If Cameron's efforts really are aimed at curtailing the abuse of children, then they are a farce.

This is because paedophiles do not obtain their pornography from the regular internet. They use specialised software to access the so-called "deep web", which consists of websites that are not indexed by search engines. Saying, as Cameron does, that companies such as Google need to "do more" to combat child pornography betrays a very poor understanding of these issues. Google already blocks any site that it feels is harmful and the real storehouses of child pornography do not fall under its area of influence.

Anyone who knows anything about the loose group of secret websites that perpetuate the spread of child pornography already knows this. So it comes as a surprise that Cameron and his supporters did not.

Followers of Cameron's way of thinking may counter criticism of the plan by pointing out that it is also intended to prevent children from accessing legal pornography and that the entire effort is going to be of an "opt-in" nature. This means that individuals can turn the censorship off if they wish to access banned content, which will include things deemed harmful to society, such as rape, but also all forms of legal pornography as well.

The problem with this argument is that they are conflating genuinely damaging material, such as those that support rape, with all forms of legal pornography. Thus, they must be including (one assumes) artwork that contains nudity. If this is the case, then overcensorship becomes almost certain. Even if the filter they employ is 99% accurate (a figure that technical experts say is laughably optimistic) it would still mean that literally millions of sites will be wrongfully banned.

Second, what do they intend to do if a website contains generally benign ingredients, with the occasional risqué picture slipped in? If those websites get a free pass, then the filter is meaningless. But if those websites get banned en masse, then Facebook, Twitter, YouTube, 9Gag, Instagram and Tumblr will all be censored.

This brings us to a further problem: this form of censorship erodes "net neutrality". Net neutrality is the idea that it is wrong to privilege some internet services over others and that every website should be given an equal chance to attract visitors. We currently have a high degree of net neutrality, which is a good thing.

But picture what would happen if Facebook and a tiny web start-up both found themselves on the UK's blacklist. Facebook is a multibillion-dollar business. I doubt Mark Zuckerberg's morning coffee would be cold before an army of lawyers would be paratrooped into Number 10 to ask the prime minister what the hell he thought he was doing. By contrast, a smaller web business, struggling to survive in its early days, would most likely be strangled of clients and simply die. In an environment such as this, secondary businesses that rely on websites, such as advertisers, will find themselves forced to use only the larger sites, because only they can guarantee freedom from restriction.

The truth is that the internet is too varied, too complex and too important to hand control of it over to any one group, and freedom of the internet is already being slowly eroded around the world. Australia has similar restrictive laws to those proposed by Cameron and its implementation has been racked by controversy since the start. Accusations of a lack of transparency have gone hand in hand with claims of overcensorship.

Russia, too, has a blacklist of websites-that-shall-not-be-named. I'm sure it will surprise no one to learn that the Committee to Protect Journalists has alleged that some of the banned websites are those of news organisations that dared to report on corruption in the government of Vladimir Putin.

In both the Australian and Russian cases, as in the United Kingdom, censorship laws were supposedly implemented "for the children". Well, I have bad news for parents: if your children are truly determined to find pornography, there is little you can do to stop them – and an internet blacklist will not much help. Indeed, this might be the most compelling reason to oppose an internet pornography filter: it simply will not work. No government, and certainly no service provider, has the resources to police the entire internet. If the government of Iran, which employs draconian censorship policies, is unable to keep porn away from its citizens, then it's hard to see how Cameron plans to do better.

One can, of course, automate the process by restricting certain key words, but this is actually even worse. Do you need a support group for "violent abuse"? Then I'm afraid no results will be found. Are you a registered sex therapist looking to advertise? Your phone will never ring.

But are these problems not perhaps worth it in order to combat child pornography and the abuse from which it stems? Not surprisingly, the answer is no, because law enforcement already possesses ample power to crack down on those who make or distribute child pornography or who commit other acts of child abuse.

To take the example of two recent South African cases, Johannes Kleinhans and Sifiso Makhubo, additional laws regulating the internet would not have been of any help. Kleinhans was found to be in possession of illegal imagery and he was successfully prosecuted using existing laws. The 122 cases of rape Makhubo was accused of before he killed himself in his cell last week did not involve the internet at all.

And, as the banning of Of Good Report has shown, even existing laws can go too far if they are applied haphazardly or without an appreciation of the issues at stake.

So, to my fellow South Africans and our friends in the UK, I say: we need to stop this, right now. Because censorship of the internet is catching on – even though it restricts freedom of speech and privileges the powerful – it doesn't work and doesn't help. People who support such measures do so because they believe that they will protect children. But they won't.

If you are a parent and you are concerned that your children might be exposed to something that troubles them, the only real solution is to cultivate the kind of relationship with your children so they know that, if they are unsure about something, they can always come to you for help.

Sadly, sentiments such as these do not make for catchy headlines and that is the real issue here. Cameron's efforts are not about helping children. They are a political Trojan horse, plain and simple.